Motion Speed velocity.notebook
October 12, 2011
Distance, Displacement, Motion, Speed, Velocity
Motion Speed velocity.notebook
October 12, 2011
Units
Tells us what the number means. No meaning without the unit
Distance and Displacement
• Distance: the length of a path between 2 points
• Measured in mm, cm, m, km
• Displacement: the direction from the starting point and the length of a straight line from the starting point to the ending point
• Has both direction and length
• ex. 35 miles in a north east direction
• As the crow flies
Motion Speed velocity.notebook
Linear Motion
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Motion in a straight line.
Most simple to understand
Curved motion later
RATE: a quantity divided by a time
October 12, 2011
Motion Speed velocity.notebook
October 12, 2011
Frame of Reference
• Are you moving right now?
• Frame of Reference: A system of objects that are not moving with respect to one another.
• Ex. Two cars going the same speed in the same direction
Motion Speed velocity.notebook
October 12, 2011
Relative Motion
• Relative Motion: motion in relation to a frame of reference
• Ex. People in a bus relative to people outside Motion Speed velocity.notebook
October 12, 2011
Speed/Velocity
• Speed: the ratio of the distance an object moves to the amount of time the object moves.
• distance
time
Mile/hr, meters/ second (m/s) Velocity: describes both speed and direction of motion
Motion Speed velocity.notebook
Instantaneous Speed
• Instantaneous Speed: the speed measured at a particular instant.
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Speedometer, radar gun October 12, 2011
Motion Speed velocity.notebook
October 12, 2011
Average speed
• Average speed: the computed speed for the entire duration of a trip. • The total distance traveled divided by the total time it takes to travel that distance
• Average speed = Total Distance , or v=d
Total Time t
Motion Speed velocity.notebook
October 12, 2011
Average speed
• Average speed v=d
• v = speed or velocity t
• d = distance (m, km, mi, cm, etc.)
• t = time (hr, min, s)
• ex. A car travels 100 miles in 2 hours. What is its average speed?
• ex. How long does it take a car with an average speed of 35 km/hr to travel 455 km?
• ex. How far will a person travel if they can run 5.5 m/s for 36 s?
• ex. What is the average speed of a car that travels 10 km in 5 min, then stops for 10 min, then travels 5 km in 15 min?